Elastic yarn having cover knitted upon the core



NOV. 22, 1938. LlNKE 2,137,692

ELASTIC YARN HAVING COVER KNITTED UPON THE CORE Filed Feb. 10; 1957 2 Sheets-Sheet 1 I INVENTOR.

ATTORNEYS Nov. 22, 1938. I P. A. LINKE 2,137,692

ELASTIC YARN HAVING COVER KNITTED UPON THE CORE Filed Feb. 10, 1937 2 Sheets-Sheep 2 T 4 w i jaw/4.2%

ATTORNEYS Patented Nov. 22, 1938 ELASTIC YARN HAVING COVER KNITTED UPON THE CORE a Paul A. Summit, N. 1., assignor to was States Rubber Products, Inc., New York, N. Y., a corporation of Delaware Application February 10, 1937, Serial No. male 9 Claims. (CL 66-19:)

This invention relates to an elastic yarn comprising an elastic core such as rubber and a fibrous or textile cover for the core.

Elastic yarn consisting of a rubber core hav ing one or more covers helically wound thereupon or having a cover braided about the rubber core are well known and are extensively used in elastic fabrics.

i It is found, however, that'when elastic yarn 10 having a cover that is either helically wound or braided upon the core is used and the core thereof breaks or is severed, the cover adjacent the broken end of the core tends to unwind or otherwise expose the broken end and permit the broken 15 core to contract in the fabric. This tendency of the cover to pull loose from or otherwise release the severed end of the core presents serious difiiculties particularly when it occurs after the elastic yarn is introduced in a tensioned condition in an elastic fabric. This difficulty is due largely to the fact that the textile cover upon the rubber core is relied upon to hold the core in place in the elastic fabric in a. tensioned condition. If the cover fails to hold the core in the 25 desired tensioned condition in the fabric then the contractive force of the fabric is decreased. Furthermore, if the rubber cores are not held in place in the fabric or if one or more cores becomes severed or brokemthese ends tend to pull back in 30 the fabric, and if the cover does not remain upon the broken end of the core this end is likely to project from a face of the fabric and form a defect commonly known as a black-head";

One of the principal causes of the rubber core becoming cut or broken in the fabric and pulling back, resulting in loss of tension in thefabric and theproduction offblack-heads" is due to needle cutting caused by the rubber core being cut or knicked by the' sewing machine needle 10 when the elastic fabric is sewed.

The primary feature of the present invention resides in an elastic yarn having the coverknitted thereupon. One important advantage of-an elastic yarn having the cover formed thereupon .5 in this manner is due to the fact that the operation of knitting the cover upon the core serves to tightly lock the knitted loops about the rubber core. As a result, when the rubber coreis severed or breaks the cover due to the manner in which 30 it is tightly locked thereupon will not pull back or expose the end of the rubber core. Another important advantage of the present construction resides in the fact that when the cover is knitted upon the rubber core the knitted loops thus 35 formed serve as anchoring loops adapted to hold the elasticyarn in place in the fabric. These anchoring loops are also well adapted to be interengaged and held by'the loopsof a row of stitches introduced by the sewing machine needle when the elastic fabric is sewed. A further advantage of the present construction resides in the fact that the knitted cover is well adapted to limit the stretch of the rubber core, and the outer surface of the knitted cover is somewhat rough and this helps to prevent the elastic yarn from slipping in the elastic fabric in which it may be laid or otherwise introduced. Elastic yarn constructed in accordance with the present invention may have a single cover knitted thereupon or it may have two or more covers knitted upon the elastic yarn and these knitted covers may be put on simultaneously or in separate operation. when two knitted covers are used it will be found desirable in many cases to knit these two covers simultaneously and at 2 substantially the same point upon the rubber core so that the loops of one knitted cover will more or less interlock withthose of the other cover to thereby more securely fasten both covers in place.

v If desired, one cover may be knitted upon the rubber core and a second cover may be helically wound or braided over this knitted cover thus securing the advantages of the knitted cover with istic of a helically wound or braided cover. The aboveand other features of the elastic yarn of the present invention and a manner of constructing thesamewill be more fully understood from the following description when read in connection with the accompanying drawings; wherein--' r 4 Fig. 1 is a section shown more or less diagrammatically .of mechanism for producing elastic yarn in accordance with the present invention 40 and comprising a rubber core having a single .cover knitted thereupon.

Fig. 2 is a view similar to Fig. 1 but discloses mechanism whereby two covers are knitted upon Q the rubber core by asingle needle. v

3 is a view similar to Fig. 2 but discloses mechanisms for employing twoneedles for knitting two covers upon the elastic core. Y

Fig. 4 on a. relatively large scale is a plan view of the elastic yarn constructed in accordance to withFig.1.-

Fig. 5 is a plan view showing the yarn constructed in accordance with HR. 2.

Fig. 6 is a plan-view showing theelastic yarn. constructed in accordance with Fig. 3 and v the smoothness of the outer surface character- 30 I Fig. '7 is a plan view of a piece of elastic webbing formed of the elastic yarn of the present invention and shown as sewed to another piece of fabric.

The elastic yarn or the present invention can be readily produced on a warp knitting machine of well known construction. About the only change that need be made in such machine is to provide take-up means for each strand of elastic yarn being produced, and tension let-ofi means for supplying the rubber core and covering yarn to the knitting point under the proper tension.

The ordinary warp knitting machine is provided with a series of knitting needles arranged in a row along a supporting frame. If desired each of these needles may be employed in accordance with the present invention to cover a separate rubber core or other elastic thread provided the needles are not too close together. If, however, the needles of the warp knitting machine are quite close together it may be desirable to remove every other needle to thereby provide more room for the present core covering operation.

If it is desired to apply only one knitted cover upon the elastic or rubber core and to use only a single needle to form such cover, then a rubber core to be covered may be supplied to each needle. But on the other hand, if it is desired to utilize two needles to form the cover upon each rubber core then a core may be supplied to each pair of needles.

I In either case it will be apparent that one ordinary warp knitting machine having the usual large number of needles will serve to produce simultaneously a large number of elastic yarns each consisting of a rubberbr elastic core having one or more covers knitted thereupon.

While various forms of knitting mechanism may be employed in manufacturing the elastic yarn of the present invention, the mechanism of Fig. 1 and which for the most part is of well known construction will now be described. It will be understood however that in the transverse section shown, only one elastic yarn is illustrated as being covered whereas this machine is or may be capable of producing many elastic yarns at the same time.

The machine is shown as provided with the usual latch knitting needles l0 mounted in the holder II which is bolted or otherwise secured to the needle bar l2. This bar I! is raised and lowered as usual to operate the needles In, and adjacent the bank oi. needles I0 is provided the fixed bar l3 which serves to support the work and to definethe point at which the cover is formed about thecore.

The core ll which may be formed of any suitable rubber or elastic material is supplied by a spool l5. This spool is; provided with brake means l6 for retarding its rotation to thereby tension the rubber core. The core I4 passes downwardly from the spool l5 through the guide eyes I1 and I8 provided at the opposite extremities of the guide l9, and the series of guides l9 are secured to the guide bar or cradle bar 20.

The covering yarn 2| which may be silk, cotton, wool or any other suitable textile or fibrous material is supplied by a spool 22 having the brake means 23 for retarding the unwinding op-. eration of this spool. The yarn 2| as it is' led downwardly passes'through the guide eyes 24 and 25 at the opposite ends of the guide secured to the guide bar 21.

The guide bars 20, 21 are reciprocated through a short distance in the direction 01 their length, and are also rocked to move the guide eyes I8, 25 from the full line position of Fig. 1 to the dotted line position. The guide bar 21 is so operated that the guide eye 25 will loop the covering yarn 2| about the raised needle II] as shown in Fig. and the, guide bar 20 is rocked sufficiently to cause its guide eye l8 to clear the guide eye 25.

After the yarn 2| has been looped about the raised needle 10 to lay the. yarn in the hook as shown the needle is lowered to draw this yarn loop through the previously formed yarn loop 2 la resting uponthe fixed bar I3, and as this series of operations is repeated the elastic yarn 28 comprising the rubber core l4 having the cover 2| knitted thereupon is produced. The elastic yarn 28 is drawn downward as it is produced by takeup mechanism such as the positively driven rolls 29 and 30 having between them the smaller roll 3| about which the yarn is looped. The. finished yarn may then be wound into the package 32.

The yarn take-up mechanism just described is preferably operated at a speed that will stretch the rubber core M so as to elongate it from 75% to possibly 300%, so that after the cover is applied and its tension is relieved the knitted coils will be closer together.

The construction of the elastic yarn formed upon the machine of Fig. 1 is more clearly shown in Fig. 4 wherein the elastic yarn is illustrated as stretched sufficiently to space the core encircling loops a substantial distance apart. The core I4 is preferably formed of vulcanized rubber and while it may be not more than 5 of an inch in diameter, and may be used either as a knitted yarn or as warp or weft in a woven fab- 4 ric, the present invention is designed more particularly for the construction of the large sizes of elastic yarn such as are used as laid-in elastic yarns in knitted and lace goods. The covering 2| is preferably knitted tightly about the stretched core l4 so that it will not slip or pull back thereupon and it is well adapted to limit the stretch of the rubber core, and may serve also to hold the core under some tension whenthe elastic yarn is at rest. Furthermore the nature of the cover thus formed is not as smooth as the ordinary helically wound cover or braided cover and as a result the present elastic yarn is less likely to creep or slip in a fabric than are the elastic yarns having. a smoother cover.

The construction and operation of the mechanism shown in Fig. 2 is substantially the same as that shown in Fig. 1 except that in Fig. 2 the latch needle I0 is supplied with two covering yarns33 and 34 instead of with a single covering yarn as in Fig. 1. These yarns are supplied by the spools 35 and 36 and one is supplied to the guide 26 while the other is supplied to the third guide 31 upon the guide bar 38. The guides l9.

26 'and 21 are so operated that the two covering yarns 33 and 34 are'laid together into the needle hook and are knitted together about the rubber core H as is clearly shown in Fig. 2 to form the elastic yarn 39. In this manner more yarn is placed upon the core than in Fig. 1 and the knitted loops of each yarn helps to hold the loops of the other yarn in the core covering position. The guides 26 and 21 are preferably so operated that one passes its textile yarn about the core in one direction and the other passes its textile yarnabout the core in the opposite direction to produce the balanced construction shown in Fig. 5.

nism shown in Fig. 3 is similar to that of Fig. 2 except that in Fig. 3 two needles HI and 40 are employed and first one is supplied with the covering yarns 4! and .42 and then the other is supplied with these yarns, but in this machine the core M lies between the yarns M and 42 and although bothyarns engage first one needle and then the other the loops 4i and 42 will lie at opposite sides of the core M as shown in Fig. 6. The elastic yarn 43 as it is formed passes downwardly between the spaced fixed bars M and 45 and at the outer face of one of these bars is the needle ill whereas at the outer face of the other bar is the needle 40. These needles are so operated that one is up while the other is down. The guides i9 and 3? are preferably so operated that they pass the yarns 4i and 42 about the core M in opposite direction as will be apparent from Fig. 6.

When as elastic yarn is to be knitted or used in a shuttle it is important that it be balanced; that is that it be so constructed that it will hang free and straight in the skein without twisting or kinking. The elastic yarn of Fig. 4 is likely to be unbalanced. The elastic yarn of Fig. 5 may be well balanced and will not readily unravel. The elastic yarn of Fig. 6 may have even a better balance than the construction of Fig; 5 and the loops of the construction of Fig. 6 are so well interlocked that this construction is dimcult to unravel. Furthermore the construction of Fig. 6 produces an outer cover that is nearly round.

While three forms of elastic yarn having the cover knitted thereupon are shown in the drawings it will be apparent that "various other constructions may be made within the scope of the present invention. When the core is provided with more than one knitted cover these may take the form of separate and distinct covers applied one over the other in separate and independent operations. It will also be understood that the elastic yarn constructed as herein shown and described may be provided with one or more additional covers wound, braided, or otherwise formed on the knitted cover.

In Fig. '7 of the drawings is shown a piece of elastic webbing 4! having the elastic yarns 48 constructed in accordance with the present invention extending longitudinally thereof and this elastic webbing is shown as secured to a piece of fabric 49 having the row of sewing stitches 50 extending transversely of the elastic yarns. This view will serve to illustrate how the loops of the sewing stitches 50 are adapted to interlock. with and positively hold the knitted loops of the elastic yarn 48.

It will be seen from the i'oregoing that in the present elastic yarn the cover is well looked upon the core and will not unravel or slip back to expose the end of the core as in the prior constructions. Furthermore the core will not slip in the cover when the core breaks or is out and as a result the uncut cover will serve to hold a broken core in place in the fabric, and since the cover of the present elastic ,yarn which is formed of interlocked loops is somewhat rougher than the covers employed heretofore, it will have a less tendency to slip in the fabrics than the construction used heretofore.

Having thus described my invention what 'I claim and desire to protect by Letters Patent is:

1. An elastic yarn having a core elastic material and a textile cover formed of two strands of yarn each knitted about the core in successive loops but in opposite directions so that each yarn is locked about the core by its own loops and also by the similarly knitted loops of the other yarn.

2. An elastic yarn having a core of elastic material and'a cover formed of two strands ofyarn 4. An elastic yarn having a core of elastic ma terial and a cover formed of a plurality of strands of yarn knitted in opposite directions about the core in crossing, interlocking loops extending one over the other in tightly embracing relation with the core.

5. An elastic yarn having a core of elastic ma.- terial and a cover formed of a plurality of separate strands of yarn knitted tightly about the core in opposite directions so that these strands interlock one with the other at a plurality of points circumferentially about the core.

6. An elastic yarn having a core or elastic ma-' terial and a cover formed of two separate strands of yarn knitted about the core in opposite directions so that the knitted loops of the two strands of yarn interlock one with the other.

'7. An elastic yarn having a core of elastic material and a cover formed of two strands of yarn knitted in opposite directions about the core so that their loops interlock and maintain the elas== tic yarn in a balanced condition.

8. An elastic yarn having a core of elastic material and a cover formed of two strands of yarn knitted in opposite directions about the core in interlocked loops arranged so that corresponding,

cross the in opposite directions about the core in interlocking loops.

. PAUL A LINKE. 

